Methods and arrangements for channel access in wireless networks

ABSTRACT

Embodiments may define traffic priorities to facilitate transmissions for wireless communications devices. Many embodiments comprise MAC sublayer logic to generate and transmit management frames such as beacon frames, association response frames, reassociation response frames, and probe response frames with an access category for low power consumption stations or sensor stations comprising a parameter record defining a contention window that is the earliest contention window to open amongst contention windows defined for the access categories for traffic. In some embodiments, the MAC sublayer logic may store the parameter record sets for access categories in memory, in logic, or in another manner that facilitates transmission of the frames. Some embodiments may receive and detect communications with frames comprising the access categories and store a parameter set for one or more of the access categories in a management information base.

BACKGROUND

Embodiments are in the field of wireless communications. Moreparticularly, embodiments are in the field of communications protocolsbetween wireless transmitters and receivers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of a wireless network comprising aplurality of communications devices, including multiple fixed or mobilecommunications devices;

FIG. 1A depicts an embodiment of a management frame with an enhanceddistributed channel access parameter set element for establishingcommunications between wireless communication devices;

FIG. 1B depicts an embodiment of an enhanced distributed channel accessparameter set element for establishing communications between wirelesscommunication devices;

FIG. 1C depicts an embodiment of access category parameter recordelements;

FIG. 1D depicts an embodiment of a table for enhanced distributedchannel access parameter set elements for establishing communicationsbetween wireless communication devices;

FIG. 1E depicts an embodiment of a timing diagram based upon theenhanced distributed channel access parameter set elements in FIG. 1Dfor establishing communications between wireless communication devices;

FIG. 1F depicts an alternative embodiment for an enhanced distributedchannel access parameter set element for establishing communicationsbetween wireless communication devices;

FIG. 1G depicts an alternative embodiment of a table for enhanceddistributed channel access parameter set elements for establishingcommunications between wireless communication devices;

FIG. 1H depicts an alternative embodiment for an enhanced distributedchannel access parameter set element for establishing communicationsbetween wireless communication devices;

FIG. 1I depicts an alternative embodiment of a table for enhanceddistributed channel access parameter set elements for establishingcommunications between wireless communication devices;

FIG. 2 depicts an embodiment of an apparatus to generate, transmit,receive and interpret a frame with enhanced distributed channel accessparameter set elements;

FIG. 3 depicts an embodiment of a flowchart to generate a frame withenhanced distributed channel access parameter set elements; and

FIGS. 4A-B depict embodiments of flowcharts to transmit, receive, andinterpret communications with frames with enhanced distributed channelaccess parameter set elements as illustrated in FIG. 2.

DETAILED DESCRIPTION OF EMBODIMENTS

The following is a detailed description of novel embodiments depicted inthe accompanying drawings. However, the amount of detail offered is notintended to limit anticipated variations of the described embodiments;on the contrary, the claims and detailed description are to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the present teachings as defined by the appended claims.The detailed descriptions below are designed to make such embodimentsunderstandable to a person having ordinary skill in the art.

References to “one embodiment,” “an embodiment,” “example embodiment,”“various embodiments,” etc., indicate that the embodiment(s) of theinvention so described may include a particular feature, structure, orcharacteristic, but not every embodiment necessarily includes theparticular feature, structure, or characteristic. Further, repeated useof the phrase “in one embodiment” does not necessarily refer to the sameembodiment, although it may.

As used herein, unless otherwise specified the use of the ordinaladjectives “first,” “second,” “third,” etc., to describe a commonobject, merely indicate that different instances of like objects arebeing referred to, and are not intended to imply that the objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner.

Embodiments may define traffic priorities to facilitate transmissionsfor wireless communications devices. Many embodiments comprise MACsublayer logic to generate and transmit management frames such as beaconframes. association response frames. reassociation response frames, andprobe response frames with an access category for low power consumptionstations comprising a parameter record defining a contention window thatis the earliest contention window to open amongst contention windowsdefined for the access categories for traffic. In some embodiments, theMAC sublayer logic may store the parameter record sets for accesscategories in memory. in logic, or in another manner that facilitatestransmission of the frames. Some embodiments may receive and detectcommunications with frames comprising the access categories and store aparameter set for one or more of the access categories in a managementinformation base.

Some embodiments implement Institute of Electrical and ElectronicEngineers (IEEE) 802.11 systems such as IEEE 802.11ah systems. The IEEE802.11 wireless standard defines EDCA (enhanced distributed channelaccess). which is a prioritized carrier sense multiple access withcollision avoidance (CSMA/CA) access mechanism. IEEE 802.11-2007, IEEEStandard for Information technology—Telecommunications and informationexchange between systems—Local and metropolitan area networks—Specificrequirements—Part 11: Wireless LAN Medium Access Control (MAC) andPhysical Layer (PHY) Specifications(http://standards.ieee.org/getieee802/download/802.11-2007.pdf).

The EDCA defines four access categories (AC): background (BK), besteffort (BE), video (VI), and voice (VO) to provide required quality ofservice (QoS) for applications. The idea of having different ACs is toguarantee some level of latency requirements for, e.g., voice and videoapplications. For some devices, such, as low power stations, the QoSrequirement, may not be focused on latency but may be focused onlow-power consumption by the station. A battery-powered sensor station,for instance, may compete with a station with heavy traffic to transmita packet to an access point (AP). If both traffic flows are mapped tothe same access category, the sensor station will lose the contentionfor half of the time and have to wait, in a wake state for the channelto become idle, which consumes power. A long channel access delayincreases the power consumption of the sensor station and is exacerbatedfor systems such, as IEEE 802.11ah systems that define 1 Gigahertz (GHz)or lower channel bandwidths.

As a further illustration, a low-powered station such as a sensor devicemay be powered down to a sleep state, remain in the sleep state, andpower up to a wake state when the sensor device has data to transmit.When the sensor device wakes, it will first sense the channel to see ifthe channel is idle. If the channel is busy, the sensor device continuesto sense the channel until the channel becomes idle. This consumes powerand the longer the PPDU transmission time of the other station is, themore the power consumption by the sensor device. In sub 1 GHz bandwidthoperations, due to narrower bandwidth and much lower data rate comparedto 2.4 or 5 Gigahertz (GHz) bandwidths, the physical layer protocol dataunit (PPDU) transmission time can be tens of milliseconds.

According to one embodiment, the EDCA is redefined for, e.g., IEEE802.11ah systems with sub 1 GHz bandwidth operation, to enable low-powerconsumption stations such as small battery-powered wireless devices(e.g., sensors) to use Wi-Fi to connect to the Internet with very lowpower consumption. In many embodiments, the energy consumption of lowduty cycle stations may be reduced when coexisting with traditionaldevices that have high to medium load applications (e.g. hotspot orcellular-offloading) by giving the sensor devices higher priority thanthe other traffic types and, in further embodiments, by limiting thePPDU transmission time.

In some embodiments, the EDCA access categories are redefined to removeVI and VO access categories. In some embodiments, the BK category iscombined with the BE category. In further embodiments, a new SS categoryis defined to add a category for low power consumption stations orsensor stations.

Other embodiments may redefine the EDCA access categories to assign lowpower stations to the VO category and to reassign voice traffic to theVI category. In many of these embodiments, the low power stations may beassigned to the VO category.

In still other embodiments, a new SS category is defined for low powerconsumption devices or sensor devices in addition to the currentcategories of BK, BE, VI, and VO. In such embodiments, the SS parameterrecord element values may be configured to open a contention windowprior to the contention windows for the other categories.

Some embodiments may take advantage of Wireless Fidelity (Wi-Fi) networkubiquity, enabling new applications that often require very low powerconsumption, among other unique characteristics. Wi-Fi generally refersto devices that implement the IEEE 802.11-2007 and other relatedwireless standards.

Several embodiments comprise access points (APs) for and/or clientdevices of APs or stations (STAs) such as routers, switches, servers,workstations, netbooks, mobile devices (Laptop, Smart Phone, Tablet, andthe like), as well as sensors, meters, controls, instruments, monitors,appliances, and the like. Some embodiments may provide, e.g., indoorand/or outdoor “smart” grid and sensor services. For example, someembodiments may provide a metering station to collect data from sensorsthat meter the usage of electricity, water, gas, and/or other utilitiesfor a home or homes within a particular area and wirelessly transmit theusage of these services to a meter substation. Further embodiments maycollect data from sensors for home healthcare, clinics, or hospitals formonitoring healthcare related events and vital signs for patients suchas fall detection, pill bottle monitoring, weight monitoring, sleepapnea, blood sugar levels, heart rhythms, and the like. Embodimentsdesigned for such services may generally require much lower data ratesand much lower (ultra low) power consumption than devices provided inIEEE 802.11n/ac systems.

Logic, modules, devices, and interfaces herein described may performfunctions that may be implemented in hardware and/or code. Hardwareand/or code may comprise software, firmware, microcode, processors,state machines, chipsets, or combinations thereof designed to accomplishthe functionality.

Embodiments may facilitate wireless communications. Some embodiments maycomprise low power wireless communications like Bluetooth®, wirelesslocal area networks (WLANs), wireless metropolitan area networks(WMANs), wireless personal area networks (WPAN), cellular networks,communications in networks, messaging systems, and smart-devices tofacilitate interaction between such devices. Furthermore, some wirelessembodiments may incorporate a single antenna while other embodiments mayemploy multiple antennas. For instance, multiple-input andmultiple-output (MIMO) is the use of radio channels carrying signals viamultiple antennas at both the transmitter and receiver to improvecommunication performance.

While some of the specific embodiments described below will referencethe embodiments with specific configurations, those of skill in the artwill realize that embodiments of the present disclosure mayadvantageously be implemented with other configurations with similarissues or problems.

Turning now to FIG. 1, there is shown an embodiment of a wirelesscommunication system 1000. The wireless communication system 1000comprises a communications device 1010 that may be wire line andwirelessly connected to a network 1005. The communications device 1010may communicate wirelessly with a plurality of communication devices1030, 1050, and 1055 via the network 1005. The communications device1010 may comprise an access point. The communications device 1030 maycomprise a low power communications device such as a sensor, a consumerelectronics device, a personal mobile device, or the like. Andcommunications devices 1050 and 1055 may comprise sensors, stations,access points, hubs, switches, routers, computers, laptops, netbooks,cellular phones, smart phones, PDAs (Personal Digital Assistants), orother wireless-capable devices. Thus, communications devices may bemobile or fixed. For example, the communications device 1010 maycomprise a metering substation for water consumption within aneighborhood of homes. Each of the homes within the neighborhood maycomprise a sensor such as the communications device 1030 and thecommunications device 1030 may be integrated with or coupled to a waterusage meter.

Initially, the communications device 1030 may transmit an associationrequest frame to the communications device 1010 to request associationwith the base service set represented by the communications device 1010.The communications device 1010 may respond with an association responseframe that comprises an enhanced distributed channel access (EDCA)parameter set element comprising a parameter sets defining accesscategories for data traffic. In some embodiments, the access categoriescomprise best efforts (BE) traffic and low power consumption station(SS) traffic and define the contention windows of the access categoriesto have the first contention window for the SS traffic open prior to thecontention window for the BE traffic. Thereafter, the communicationsdevice 1030 may store the parameter sets for one or both categories in amanagement information base 1032 of memory 1031 to facilitateinteraction with the communications device 1010 in accordance with theaccess categories for traffic.

Once the communications device 1030 associates with the communicationsdevice 1010, the communications device 1030 may periodically enter anactive state or a wake state to transmit data collected such as datarelated to water usage monitored by the integrated water usage sensor.Upon entering the wake state, the communications device 1030 may waitfor a DIFS (distributed coordination function (DCF) interframe space)time unit, back off a number of time slots to determine the opening of acontention time window to the communications device 1010. Thecommunications device 1030 may then transmit one or more data frames tothe communications device 1010 of the metering substation to transmitdata related to water usage.

In some embodiments, the physical layer protocol data unit transmissiontime may be limited. For instance, the PPDU transmission time may belimited to be less than T milliseconds. If the transmission is longerthan the threshold T milliseconds, the packet may be fragmented so thatone PPDU transmission does not consume too much airtime.

In further embodiments, the communications device 1010 may facilitatedata offloading. For example, communications devices that are low powersensors may include a data offloading scheme to, e.g., communicate viaWi-Fi, another communications device, a cellular network, or the likefor the purposes of reducing power consumption consumed in waiting foraccess to, e.g., a metering station and/or increasing availability ofbandwidth. Communications devices that receive data from sensors such asmetering stations may include a data offloading scheme to, e.g.,communicate via Wi-Fi, another communications device, a cellularnetwork, or the like for the purposes of reducing congestion of thenetwork 1005.

The network 1005 may represent an interconnection of a number ofnetworks. For instance, the network 1005 may couple with a wide areanetwork such as the Internet or an intranet and may interconnect localdevices wired or wirelessly interconnected via one or more hubs,routers, or switches. In the present embodiment, network 1005communicatively couples communications devices 1010, 1030, 1050, and1055.

The communication devices 1010 and 1030 comprise memory 1011 and 1031,and Media Access Control (MAC) sublayer logic 1018 and 1038,respectively. The memory 1011 and 1031 may comprise a storage mediumsuch as Dynamic Random Access Memory (DRAM), read only memory (ROM),buffers, registers, cache, flash memory, hard disk drives, solid-statedrives, or the like. The memory 1011 and 1031 may store the framesand/or frame structures, or portions thereof such as a management framestructure and enhanced distributed channel access parameter set elementsuch as the parameter set elements 1080, 1400 and 1600 illustrated inFIGS. 1B, F, and H. Furthermore, the memory 1011 and 1031 may comprisedata to relate values of the parameter set element and parameter recordswith access categories such as the parameter values illustrated intables 1200, 1500, and 1700 in FIGS. 1D, G, and I. For example, thememory 1011, 1031 may comprise an indication of values for a minimumcontention window (aCWmin), a maximum contention window value (aCWmax),and an arbitration interframe space number (AIFSN) for access categories(AC): AC_BK, AC_BE, AC_VI, and AC_VO: Note that these tables includevalues that are illustrative so embodiments may use these values and/orother values.

The MAC sublayer logic 1018, 1038 may comprise logic to implementfunctionality of the MAC sublayer of the data link layer of thecommunications device 1010, 1030. The MAC sublayer logic 1018, 1038 maygenerate the frames such as management frames and the physical layerlogic 1019, 1039 may generate physical layer protocol data units (PPDUs)based upon the frames. More specifically, the frame builders 1013 and1033 may generate frames with an

EDCA parameter set element 1014, 1034 and the data unit builders of thephysical layer logic 1019, 1039 may encapsulate the frames withpreambles to generate PPDUs for transmission via a physical layer devicesuch as the transceivers (RX/TX) 1020 and 1040.

The communications devices 1010, 1030, 1050, and 1055 may each comprisea transceiver such as transceivers 1020 and 1040. Each transceiver 1020,1040 comprises an RF transmitter and an RF receiver. Each RF transmitterimpresses digital data onto an RF frequency for transmission of the databy electromagnetic radiation. An RF receiver receives electromagneticenergy at an RF frequency and extracts the digital data therefrom.

FIG. 1 may depict a number of different embodiments including aMultiple-Input, Multiple-Output (MIMO) system with, e.g., four spatialstreams, and may depict degenerate systems in which one or more of thecommunications devices 1010, 1030, 1050, and 1055 comprise a receiverand/or a transmitter with a single antenna including a Single-Input,Single Output (SISO) system, a Single-Input, Multiple Output (SIMO)system, and a Multiple-Input, Single Output (MISO) system.

In many embodiments, transceivers 1020 and 1040 implement orthogonalfrequency-division multiplexing (OFDM). OFDM is a method of encodingdigital data on multiple carrier frequencies. OFDM is afrequency-division multiplexing scheme used as a digital multi-carriermodulation method. A large number of closely spaced orthogonalsub-carrier signals are used to carry data. The data is divided intoseveral parallel data streams or channels, one for each sub-carrier.Each sub-carrier is modulated with a modulation scheme at a low symbolrate, maintaining total data rates similar to conventionalsingle-carrier modulation schemes in the same bandwidth.

An OFDM system uses several carriers, or “tones,” for functionsincluding data, pilot, guard, and nulling. Data tones are used totransfer information between the transmitter and receiver via one of thechannels. Pilot tones are used to maintain the channels, and may provideinformation about time/frequency and channel tracking. Guard tones maybe inserted between symbols such as the short training field (STF) andlong training field (LTF) symbols during transmission to avoidinter-symbol interference (ISI), which might result from multi-pathdistortion. These guard tones also help the signal conform to a spectralmask. The nulling of the direct component (DC) may be used to simplifydirect conversion receiver designs.

In some embodiments, the communications device 1010 optionally comprisesa Digital Beam Former (DBF) 1022, as indicated by the dashed lines. TheDBF 1022 transforms information signals into signals to be applied toelements of an antenna array 1024. The antenna array 1024 is an array ofindividual, separately excitable antenna elements. The signals appliedto the elements of the antenna array 1024 cause the antenna array 1024to radiate one to four spatial channels. Each spatial channel so formedmay carry information to one or more of the communications devices 1030,1050, and 1055. Similarly, the communications device 1030 comprises atransceiver 1040 to receive and transmit signals from and to thecommunications device 1010. The transceiver 1040 may comprise an antennaarray 1044 and, optionally, a DBF 1042.

FIG. 1A depicts an embodiment of a management frame 1060 forcommunications between wireless communication devices such ascommunications devices 1010, 1030, 1050, and 1055 in FIG. 1. Themanagement frame 1060 may comprise a MAC header 1061, a frame body 1074,and a frame check sequence (FCS) field 1076. The MAC header 1061 maycomprise the frame control field 1062 and other MAC header fields 1068.The frame control field 1062 may be two octets and may identify the typeand subtype of the frame such as a management type and, e.g., areassociation response frame subtype. The other MAC header fields 1068may comprise, for example, one or more address fields, identificationfields, control fields, or the like.

In some embodiments, such as embodiments, the management frame 1060 maycomprise a frame body 1074. The frame body 1074 may be a variable numberof octets and may include data elements, control elements, or parametersand capabilities. In the present embodiment, the frame body 1074comprises an enhanced distributed channel access (EDCA) parameter setelement 1080. FIG. 1B illustrates an embodiment of an EDCA parameter setelement 1080.

The EDCA parameter set element 1080 may be used by the access point (AP)to establish policy by changing default management information base(MIB) attribute values, to change policies when accepting new stations(STAs) or new traffic, or to adapt to changes in offered load. The mostrecent EDCA parameter set element 1080 received by a non-AP STA may beused to update the appropriate MIB values.

The EDCA parameter set element 1080 may comprise fields such as anelement identifier (ID) field 1082, a length field 1086, a quality ofservice (QoS) information (info) field 1088, a reserved field 1090, andparameter record elements including AC_BE parameter record 1092 andAC_SS parameter record 1094. The element ID field 1082 may be one octetand may identify the element as an EDCA parameter set element 1080. Thelength field 1086 may be one octet and may define the length of the EDCAparameter set element 1080. The QoS info field 1088 may be one octet andmay contain the EDCA Parameter Set Update Count subfield, which mayinitially be set to 0 and may be incremented each time any of the ACparameters changes. The EDCA Parameter Set Update Count subfield may beused by non-AP STAs to determine whether the EDCA parameter set haschanged and requires updating the appropriate MIB attributes. Thereserved field 1090 may be one octet and may be reserved for future use.

The EDCA parameter set element 1080 may also comprise parameter recordsfor each access category including, in the present embodiment, an AC_BEparameter record 1092 and an AC_SS parameter record 1094. In the presentembodiment, the voice and video access categories (AC_VI and AC_VO) areremoved. Also, AC_BK and AC_BE may be combined into one AC_BE forsimplicity. Furthermore, a new sensor access category (AC_SS) is added.

The parameter records may each comprise fields such as the fieldsillustrated in parameter record elements 1100 in FIG. 1C. The values forthe parameter record elements access category index/arbitrationinterframe space number (ACl/AIFSN) 1104, encoded contention windowminimum/maximum (ECWmin/ECWmax) 1106 of the AC_BE parameter record 1092and the AC_SS parameter record 1094 are illustrated in the accesscategory parameter table 1200 in FIG. 1D. Note that the AIFSN, in thepresent embodiment, for the best-effort access category, AIFSN [AC_BE],may be increased to 10 so that the sensor traffic has the priority overthe best effort traffic when competing in the first round of contention(assuming aCWmin value is 15).

The transmission operations (TXOP) limit 1108 may be specified as anunsigned integer, with the least significant octet transmitted first, inunits of, e.g., 32 μs. A TXOP Limit 1108 field value of 0 indicates thata single MAC service data unit (MSDU) or MAC management protocol dataunit (MMPDU), in addition to a possible request to send/clear to send(RTS/CTS) exchange or CTS to itself, may be transmitted at any rate foreach TXOP.

Referring again to FIG. 1A, in many embodiments, the management frame1060 may comprise a frame check sequence (FCS) field 1076. The FCS field1076 may be four octets and may include extra checksum characters addedto the short frame 1060 for error detection and correction.

FIG. 1E depicts an embodiment of a timing diagram 1300 for the channelaccess relationship between AC_BE and AC_SS transmissions for accesscategories illustrated in table 1200 in FIG. 1D. As illustrated, asensor STA and a hotspot STA are competing with each other for thechannel. The sensor STA has sensor traffic mapped to AC_SS and thehotspot STA has best effort traffic mapped to AC_BE. Once the channelbecomes idle, the two STAs will start defer+backoff. The sensor STA willdefer for AIFS [AC_SS], which is equal to SIFS plus 2 times slot-timeand then do backoff with the random number chosen from CW=[0, 7]. Inthis example, we assume the sensor STA chose the random number three.

The hotspot STA, on the other hand, will first defer for AIFS[AC_BE],which equals SIFS plus 10 times slot-time and then start doing thebackoff. However, since the defer+backoff for the sensor STA is alwaysless than AIFS [AC_BE], the sensor STA will always win the first roundof contention. Furthermore, for situations in which the duty-cycle ofthe sensor traffic is very low (e.g. a packet transmission every fewminutes), providing AC_SS with the highest priority will notsignificantly impede the AC_BE applications and the effect may benegligible.

Furthermore, if the PPDU transmission time (T) is too long (e.g., T>5milliseconds), a sensor STA may have to wait too long to access thechannel. For data rates below 1 Mbps, for example, it is easy to havevery long PPDU transmission times with the packet size of a couple ofhundreds of bytes. According to many embodiments, the PPDU transmissiontime may be limited so that the sensor STA does not need to wait toolong for the channel to be idle, which will save power consumption bythe sensor STA.

FIGS. 1F and 1G illustrate an alternative embodiment of an EDCAparameter set element 1400 and access category parameter table 1500comprising values for the parameter record elements of the EDCAparameter set element 1400. According to the present embodiment, anotherway to provide sensor devices with the highest priority, or have thefirst open contention window, is to use all four access categories inthe existing EDCA parameter set but to have different mapping betweenaccess categories and the traffic types with modified EDCA parameters.

The EDCA parameter set element 1400 may comprise fields such as anelement identifier (ID) field 1402, a length field 1406, a quality ofservice (QoS) information (info) field 1408, a reserved field 1410, andparameter record elements including AC_BK parameter record 1412, AC_BEparameter record 1414, AC_VI parameter record 1416, and AC_VO parameterrecord 1418. The AC_BK parameter record 1412, AC_BE parameter record1414, AC_VI parameter record 1416, and AC_VO parameter record 1418 maycomprise values as those illustrated in table 1500 of FIG. 1G.

The element ID field 1402 may be one octet and may identify the elementas an EDCA parameter set element 1400. The length field 1406 may be oneoctet and may define the length of the EDCA parameter set element 1400.The QoS info field 1408 may be one octet and may contain the EDCAParameter Set Update Count subfield. And the reserved field 1410 may beone octet and may be reserved for future use.

FIGS. 1H and 1I illustrate an alternative embodiment of an EDCAparameter set element 1600 and access category parameter table 1700comprising values for the parameter record elements of the EDCAparameter set element 1600. According to the present embodiment, anotherway to provide sensor devices with the highest priority, or have thefirst open contention window, is to add the new sensor access category(AC_SS) to the existing access category table and have different EDCAparameters.

The EDCA parameter set element 1600 may comprise fields such as anelement identifier (ID) field 1602, a length field 1606, a quality ofservice (QoS) information (info) field 1608, a reserved field 1610, andparameter record elements including AC_BK parameter record 1612, AC_BEparameter record 1614, AC_VI parameter record 1616, AC_VO parameterrecord 1618, and AC_SS parameter record 1620. The AC_BK parameter record1612, AC_BE parameter record 1614, AC_VI parameter record 1616, AC_VOparameter record 1618, and AC_SS parameter record 1620 may comprisevalues as those illustrated in table 1700 of FIG. 1I.

The element ID field 1602 may be one octet and may identify the elementas an EDCA parameter set element 1600. The length field 1606 may be oneoctet and may define the length of the EDCA parameter set element 1600.The QoS info field 1608 may be one octet and may contain the EDCAParameter Set Update Count subfield. And the reserved field 1610 may beone octet and may be reserved for future use.

Note that the values shown in the tables 1200, 1500, and 1700 are forillustrative purposes and may be other values.

FIG. 2 depicts an embodiment of an apparatus to generate, transmit,receive, and interpret an enhanced distributed channel access (EDCA)parameter set element in a frame. The apparatus comprises a transceiver200 coupled with Medium Access Control (MAC) sublayer logic 201. The MACsublayer logic 201 may determine a frame and the physical layer (PHY)logic 250 may determine the PPDU by encapsulating the frame with apreamble to transmit via transceiver 200.

In many embodiments, the MAC sublayer logic 201 may comprise a framebuilder 202 to generate frames (MPDUs) such as one of the managementframe 1060 with EDCA parameter set elements 1080, 1400, and 1600illustrated in FIGS. 1A-I. The EDCA parameter set elements may comprisedata indicative of traffic priorities for the access point within whichthe apparatus resides. The access point such as communications device1010 and a station such as communications device 1030 in FIG. 1 maymaintain the EDCA parameter set elements 1080, 1400, and 1600 and valuesin memory such as the management information base (MIB) 1032 illustratedin FIG. 1.

The PHY logic 250 may comprise a data unit builder 203. The data unitbuilder 203 may determine a preamble to encapsulate the MPDU to generatea PPDU. In many embodiments, the data unit builder 203 may create thepreamble based upon communications parameters chosen through interactionwith a destination communications device.

The transceiver 200 comprises a receiver 204 and a transmitter 206. Thetransmitter 206 may comprise one or more of an encoder 208, a modulator210, an OFDM 212, and a DBF 214. The encoder 208 of transmitter 206receives and encodes data destined for transmission from the MACsublayer logic 202 with, e.g., a binary convolutional coding (BCC), alow density parity check coding (LDPC), and/or the like. The modulator210 may receive data from encoder 208 and may impress the received datablocks onto a sinusoid of a selected frequency via, e.g., mapping thedata blocks into a corresponding set of discrete amplitudes of thesinusoid, or a set of discrete phases of the sinusoid, or a set ofdiscrete frequency shifts relative to the frequency of the sinusoid. Theoutput of modulator 210 is fed to an orthogonal frequency divisionmultiplexer (OFDM) 212, which impresses the modulated data frommodulator 210 onto a plurality of orthogonal sub-carriers. And, theoutput of the OFDM 212 may be fed to the digital beam former (DBF) 214to form a plurality of spatial channels and steer each spatial channelindependently to maximize the signal power transmitted to and receivedfrom each of a plurality of user terminals.

The transceiver 200 may also comprise diplexers 216 connected to antennaarray 218. Thus, in this embodiment, a single antenna array is used forboth transmission and reception. When transmitting, the signal passesthrough diplexers 216 and drives the antenna with the up-convertedinformation-bearing signal. During transmission, the diplexers 216prevent the signals to be transmitted from entering receiver 204. Whenreceiving, information bearing signals received by the antenna arraypass through diplexers 216 to deliver the signal from the antenna arrayto receiver 204. The diplexers 216 then prevent the received signalsfrom entering transmitter 206. Thus, diplexers 216 operate as switchesto alternately connect the antenna array elements to the receiver 204and the transmitter 206.

The antenna array 218 radiates the information bearing signals into atime-varying, spatial distribution of electromagnetic energy that can bereceived by an antenna of a receiver. The receiver can then extract theinformation of the received signal.

The transceiver 200 may comprise a receiver 204 for receiving,demodulating, and decoding information bearing signals. The receiver 204may comprise one or more of a DBF 220, an OFDM 222, a demodulator 224and a decoder 226. The received signals are fed from antenna elements218 to a Digital Beam Former (DBF) 220. The DBF 220 transforms N antennasignals into L information signals. The output of the DBF 220 is fed tothe OFDM 222. The OFDM 222 extracts signal information from theplurality of subcarriers onto which information-bearing signals aremodulated. The demodulator 224 demodulates the received signal,extracting information content from the received signal to produce anun-demodulated information signal. And, the decoder 226 decodes thereceived data from the demodulator 224 and transmits the decodedinformation, the MPDU, to the MAC sublayer logic 201.

Persons of skill in the art will recognize that a transceiver maycomprise numerous additional functions not shown in FIG. 2 and that thereceiver 204 and transmitter 206 can be distinct devices rather thanbeing packaged as one transceiver. For instance, embodiments of atransceiver may comprise a Dynamic Random Access Memory (DRAM), areference oscillator, filtering circuitry, synchronization circuitry, aninterleaver and a deinterleaver, possibly multiple frequency conversionstages and multiple amplification stages, etc. Further, some of thefunctions shown in FIG. 2 may be integrated. For example, digital beamforming may be integrated with orthogonal frequency divisionmultiplexing.

The MAC sublayer logic 201 may parse the MPDU to determine theparticular type of frame and identify the EDCA parameter set element.The MAC sublayer logic 201 may determine the QoS info field value of theEDCA parameter set element to determine whether information in the EDCAparameter set element has changed, thus requiring that the MIB beupdated. For instance, if the count in the EDCA Parameter Set UpdateCount subfield has changed since the last time the MIB was updated, theMAC sublayer logic 201 may determine that the MIB should be updated. Onthe other hand, if the count has not changed, the MIB may not need to beupdated and the EDCA parameter set element may be discarded.

In some embodiments, the MPDU may comprise an element such as aninformation element defining a PPDU threshold transmission time. In suchembodiments, the PPDU transmission time may be limited to be less than,e.g., T milliseconds. If the transmission for a PPDU may be longer thanthis threshold T milliseconds, the MAC sublayer logic 201 may fragmentthe packet so that one PPDU transmission does not consume more air-timethan the PPDU threshold transmission time of, e.g., T milliseconds.

FIG. 3 depicts an embodiment of a flowchart 300 to generate or otherwisedetermine a management frame with an EDCA parameter set element such asthe EDCA parameter set elements 1080, 1400, and 1600 described in FIGS.1A-I. The flowchart 300 begins with a medium access control (MAC)sublayer logic determining a MAC header for a management frame (element305).

The MAC sublayer logic may determine the EDCA parameter set element,which comprises determining a parameter record element for sensorsand/or other low power devices (element 310). For instance, the MACsublayer logic may access memory to retrieve an element structure forthe EDCA parameter record set elements and assign the elements valuessuch as the AIFSN, aCWmin, and aCWmax to establish a contention windowfor the low power consumption devices or sensors that opens prior to thecontention windows for other access categories. In many embodiments, thecontention window for the low power consumption devices or sensorscloses prior to a contention window for another access category opening.For situations in which the low power consumption devices or sensors arelow duty cycle, interference and latencies caused by the low duty cycledevices may be non-existent, negligible or otherwise tolerable bydevices in the other access categories. In further embodiments, theAIFSN for the low power consumption devices or sensors may be lower thanthe AIFSNs for other access categories. And, in further embodiments, thelow power consumption devices or sensors may otherwise be given thehighest priority of the access categories.

The MAC sublayer logic may determine other elements of the managementframe body frame (element 325). In many embodiments, determining thefields may comprise retrieving these fields from a storage medium forinclusion in a frame. In other embodiments, the values to include insuch fields may be stored in a storage medium such as a read onlymemory, random access memory, a cache, a buffer, a register, or thelike. In further embodiments, one or more of the fields may be hardcodedinto the MAC sublayer logic, PHY logic, or may otherwise be availablefor insertion into a frame. In still other embodiments, the MAC sublayerlogic may generate the values of the fields based upon access toindications of the values for each.

After determining the other portions of the short frame, the MACsublayer logic may determine a frame check sequence (FCS) field value(element 335) to provide for error corrections in bit sequences receivedby the receiving device.

FIGS. 4A-B depict embodiments of flowcharts 400 and 450 to transmit,receive, and interpret communications with a management frame with anEDCA parameter set element such as the EDCA parameter set elements 1080,1400, and 1600 illustrated in FIGS. 1A-I. Referring to FIG. 4A, theflowchart 400 may begin with receiving a frame from the frame buildercomprising the EDCA parameter set element. The MAC sublayer logic of thecommunications device may generate the frame as a management frame totransmit to an access point and may pass the frame as an MPDU to a dataunit builder that transforms the data into a packet that can betransmitted to the access point. The data unit builder may generate apreamble to encapsulate the PSDU (the MPDU from the frame builder) toform a PPDU for transmission (element 405). In some embodiments, morethan one MPDU may be encapsulated in a PPDU. In many embodiments, thephysical layer logic may fragment the PPDU if transmission of the PPDUwill take longer than a threshold transmission time for transmitting thePPDU.

The PPDU may then be transmitted to the physical layer device such asthe transmitter 206 in FIG. 2 or the transceiver 1020,1040 in FIG. 1 sothe PPDU may be converted to a communication signal (element 410). Thetransmitter may then transmit the communication signal via the antenna(element 415).

Referring to FIG. 4B, the flowchart 450 begins with a receiver of anaccess point such as the receiver 204 in FIG. 2 receiving acommunication signal via one or more antenna(s) such as an antennaelement of antenna array 218 (element 455). The receiver may convert thecommunication signal into an MPDU in accordance with the processdescribed in the preamble (element 460). More specifically, the receivedsignal is fed from the one or more antennas to a DBF such as the DBF220. The DBF transforms the antenna signals into information signals.The output of the DBF is fed to OFDM such as the OFDM 222. The OFDMextracts signal information from the plurality of subcarriers onto whichinformation-bearing signals are modulated. Then, the demodulator such asthe demodulator 224 demodulates the signal information via, e.g., BPSK,16-QAM, 64-QAM, 256-QAM, QPSK, or SQPSK. And the decoder such as thedecoder 226 decodes the signal information from the demodulator via,e.g., BCC or LDPC, to extract the MPDU (element 460) and transmits theMPDU to MAC sublayer logic such as MAC sublayer logic 202 (element 465).

The MAC sublayer logic may determine the value of the QoS info field ofthe EDCA parameter set element from the MPDU (element 470). Forinstance, the MAC sublayer logic may determine if the QoS info valueindicates that the EDCA parameter set element has been updated or ifthis is the first EDCA parameter set element received for thisassociation. If the element is updated or is the first one received fromthe AP, the remainder of the values from the EDCA parameter set elementmay be determined from the MPDU and used to update the managementinformation base.

Another embodiment is implemented as a program product for implementingsystems and methods described with reference to FIGS. 1-4. Someembodiments can take the form of an entirely hardware embodiment, anentirely software embodiment, or an embodiment containing both hardwareand software elements. One embodiment is implemented in software, whichincludes but is not limited to firmware, resident software, microcode,etc.

Furthermore, embodiments can take the form of a computer program product(or machine-accessible product) accessible from a computer-usable orcomputer-readable medium providing program code for use by or inconnection with a computer or any instruction execution system. For thepurposes of this description, a computer-usable or computer readablemedium can be any apparatus that can contain, store, communicate,propagate, or transport the program for use by or in connection with theinstruction execution system, apparatus, or device.

The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device). Examples ofa computer-readable medium include a semiconductor or solid-statememory, magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and anoptical disk. Current examples of optical disks include compactdisk—read only memory (CD-ROM), compact disk—read/write (CD-R/W), andDVD.

A data processing system suitable for storing and/or executing programcode will include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution.

The logic as described above may be part of the design for an integratedcircuit chip. The chip design is created in a graphical computerprogramming language, and stored in a computer storage medium (such as adisk, tape, physical hard drive, or virtual hard drive such as in astorage access network). If the designer does not fabricate chips or thephotolithographic masks used to fabricate chips, the designer transmitsthe resulting design by physical means (e.g., by providing a copy of thestorage medium storing the design) or electronically (e.g., through the

Internet) to such entities, directly or indirectly. The stored design isthen converted into the appropriate format (e.g., GDSII) for thefabrication.

The resulting integrated circuit chips can be distributed by thefabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case, the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case, the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product.

It will be apparent to those skilled in the art having the benefit ofthis disclosure that the present disclosure contemplates methods andarrangements for channel access for wireless communications. It isunderstood that the form of the embodiments shown and described in thedetailed description and the drawings are to be taken merely asexamples. It is intended that the following claims be interpretedbroadly to embrace all variations of the example embodiments disclosed.

1. A method comprising: generating, by a medium access control sublayerlogic, a frame comprising parameter records to define access categoriesfor traffic, wherein an access category for low power consumptionstations comprises a parameter record defining a contention window thatis the earliest contention window to open amongst contention windowsdefined for the access categories for traffic; and encapsulating, byphysical layer logic, the frame with a preamble to create a physicallayer protocol data unit to transmit.
 2. The method of claim 1, furthercomprising transmitting, by the antenna, the frame encapsulated by thepreamble.
 3. The method of claim 1, further comprising storing, by themedium access control sublayer logic, at least part of the frame inmemory.
 4. The method of claim 1, wherein generating the frame comprisesgenerating the frame defining a threshold transmission time fortransmitting the physical layer protocol data unit.
 5. The method ofclaim 1, wherein generating the frame comprises generating the frame,wherein the parameter record for the access category for low powerconsumption stations defines the highest priority for traffic amongstthe access categories for traffic.
 6. The method of claim 1, whereingenerating the frame comprises generating the frame defining the accesscategory for low power consumption stations with an arbitrationinterframe space number setting that is lower than an arbitrationinterframe space number for a best efforts access category of the accesscategories for traffic.
 7. A device comprising: a memory; a mediumaccess control sublayer logic coupled with the memory to generate aframe comprising parameter records to define access categories fortraffic, wherein an access category for low power consumption stationscomprises a parameter record defining a contention window that is theearliest contention window to open amongst contention windows definedfor the access categories for traffic.
 8. The device of claim 7, furthercomprising a transmitter coupled with the medium access control logic totransmit the frame.
 9. The device of claim 9, further comprising anantenna coupled with the transmitter to transmit the frame.
 10. Thedevice of claim 7, wherein the medium access control sublayer logic iscoupled with the memory to store at least a portion of the frame. 11.The device of claim 7, wherein the medium access control logic compriseslogic to generate the frame to define a threshold transmission time fortransmitting the physical layer protocol data unit.
 12. The device ofclaim 7, wherein the medium access control logic comprises logic togenerate the frame to define the access category for low powerconsumption stations with the highest priority for traffic amongstdefined access categories.
 13. The device of claim 7, wherein the mediumaccess control logic comprises logic to generate the frame to define theaccess category with an arbitration interframe space number setting thatis lower than an arbitration interframe space number for a best effortsaccess category.
 14. A method comprising: receiving, by a medium accesscontrol sublayer logic, a frame comprising parameter records to defineaccess categories for traffic, wherein an access category for low powerconsumption stations comprises a parameter record defining a contentionwindow that is the earliest contention window to open amongst contentionwindows defined for the access categories for traffic; and storing, bythe medium access control sublayer logic, based upon the frame, theparameter record for the access category for the low power consumptionstations in a management information base in memory.
 15. The method ofclaim 14, further comprising receiving, by the antenna, the frameencapsulated by the preamble.
 16. The method of claim 14, furthercomprising storing in memory, by the medium access control sublayerlogic, a threshold transmission time defined in the frame fortransmitting a physical layer protocol data unit.
 17. The method ofclaim 14, further comprising determining the parameter record for theaccess category for low power consumption stations defines the highestpriority for traffic amongst the access categories for traffic.
 18. Themethod of claim 14, further comprising determining the frame defines theaccess category for low power consumption stations with an arbitrationinterframe space number setting of two.
 19. The method of claim 14,wherein determining the frame defines the access category for low powerconsumption stations with a minimum contention window setting of(aCWmin+1)/2−1.
 20. The method of claim 14, wherein determining theframe defines the access category for low power consumption stationswith a maximum contention window setting of aCWmax.
 21. A devicecomprising: a memory; a medium access control sublayer logic coupledwith the memory to receive a frame comprising parameter records todefine access categories for traffic, wherein an access category for lowpower consumption stations comprises a parameter record defining acontention window that is the earliest contention window to open amongstcontention windows defined for the access categories for traffic; and tostore, based upon receipt of the frame, the parameter record for theaccess category for the low power consumption stations in a managementinformation base in memory. 22-24. (canceled)
 25. The device of claim21, wherein the medium access control logic comprises logic to determinethe parameter record for the access category for low power consumptionstations that defines the highest priority for traffic amongst theaccess categories for traffic.
 26. The device of claim 21, wherein themedium access control logic comprises logic to determine that the framedefines the access category for low power consumption stations with anarbitration interframe space number setting of two.
 27. The device ofclaim 21, wherein the medium access control logic comprises logic todetermine that the frame defines the access category for low powerconsumption stations with a minimum contention window setting of(aCWmin+1)/4−1.
 28. A machine-accessible product comprising: a mediumcontaining parameter records to define access categories for traffic,wherein the parameter records: define a parameter record for an accesscategory for low power consumption stations defining a contention windowthat is the earliest contention window to open amongst contentionwindows defined for the access categories for traffic. 29-30. (canceled)